Smoke-consuming furnace.



No. 799,990. 'PATENTED SEPT. 19,1905. J. w. ALLAN. SMOKE CONSUMING FURNAGE.

APPLICATION FILED 11133.22, 1905.

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UNITED STATES PATENT OFFICE.

JOHN WV. ALLAN, OF MINNEAPOLIS, MINNESOTA, ASSIGNOR OF ONE-FOURTH TO O. W. GETOHELL, ONE-FOURTH TO F. M. OVERHOLT, AND ONE- FOURTH TO WILLIAM McMILLAN, OF MINNEAPOLIS, MINNESOTA.

Specification of Letters Patent.

Patented Sept. 19, 1905.

Application filed AP1I122,1905- Serial NO- 256,830-

I boiler-furnaces; and the object I have in view is to provide means whereby in such a furnace a complete combustion of the fuel may be obtained.

Another object of the invention is to lessen the amount of fuel required to produce the desired steam-pressure in the boiler.

Other objects of the invention will appear from. the following detailed description, taken in connection with the accompanying drawings, in which- Figure 1 is a longitudinal vertical section on the line 00 w of Fig. 2 of a boiler-furnace embodying my invention. Fig. 2 is a transverse vertical section on the line y 1/ of Fig. 1. Fig. 3 is a front elevation of the same. Fig. 4 is a detail showing a modified arrangement of the air-ducts.

In the drawings, 2 represents a tubular boiler of ordinary type; 3, the brickwork setting or furnace; 4, the grate; 5, the bridge-wall; 6, the ash-pit; 7 7, the fuel-doors, and'8 8 the ash-pit doors. All of these parts are of any preferred or ordinary construction.

Arranged above the grate and below the boiler is an arch 9., extending from the front of the combustion-chamber to a point above the rear portion of the bridge-wall. This arch is preferably formed of suitable firebrick and is provided with one or more longitudinal ducts or ports 10, extending from the front of the furnace to a point above the rear end of the grate, where said ports are connected by suitable openings with the combustion-chamber of the furnace. Suitable dampers 11 are provided for regulating the admission of air to these ports, I have shown the ports in Fig. 1 formed Within the arch itself; but, if preferred, they may be embodied in separate conductors arranged in the space between the arch and the under side of the boiler, as shown in Fig. 4. I have shown two of these ports or conductors, but do not limit myself to any particular number, as a greater or less number may be used, according to the requirements of any particular furnace. The air entering these ports becomes highly heated before mingling with the products of combustion in the combustion-chamber. The space between the arch and the boiler, which I designate by reference-numeral 12, forms aflue or passage leading from the back end of the arch, between it and the boiler, to the front end of the furnace, where it communicates with the chimney through ports 13, provided in the wall of the boiler. This passage allows the heated gases to pass through beneath the boiler to the said ports and permits the entire heating-surface of the boiler to be utilized. When the gases reach the forward end of the passage, they will flow through the ports 13 and mingle with the waste gases that have entered at the rear end of the boiler. The arch effectually separates the combustion-chamber from the bottom of the boiler and screens it from direct contact with the fiames and prevents the deposit of particles of carbon thereon, but at the same time does not reduce the heating-surface of the boiler. The bricks forming the arch will be heated to an incandescence, and the unconsumed particles of carbon coming in contact with the heated bricks will be raised to a high temperature and traveling along said arch until they reach the point where the air is introduced through the ports 10 will mingle therewith and be immediately and completely consumed. A much more perfect combustion of the fuel is thereby obtained, and I have found that a large percentage of fuel can be saved in the production of a given amount of steam. I am also able to burn a poor grade of soft coal Without producing black smoke. I claim as my invention 1. The combination in a steam-boiler furnace with a combustion-chamber and grate allowed to flow through said passage beneath the boiler and mingle with the gases which have entered the boiler at its rear end, and an air-duct extending above the lower surface of the arch from the front of the boiler and communicating with the combustion-chamber at a point above the rear of the grate, substantially as described.

2. The combination in a steam-boiler furnace with a combustion-chamber and a grate 4 and bridge-wall 5 located beneath the middle portion of the boiler, of an arch 9 arranged over said chamber and separating it from said boiler and extending from the front of said boiler to a point'above the rear of said Wall there being a passage 12 formed between said arch and boiler open at its rear end and communicating at its forward end With openings 13 in the boiler-wall leading to the chimney whereby the heated gases are allowed to flow therethrough beneath the boiler and mingle with those entering the rear end of the boiler, 

